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Titolo:
Presence of acetyl coenzyme A (CoA) carboxylase and propionyl-CoA carboxylase in autotrophic Crenarchaeota and indication for operation of a 3-hydroxypropionate cycle in autotrophic carbon fixation
Autore:
Menendez, C; Bauer, Z; Huber, H; Gadon, N; Stetter, KO; Fuchs, G;
Indirizzi:
Univ Freiburg, Inst Biol 2, D-79104 Freiburg, Germany Univ Freiburg Freiburg Germany D-79104 Biol 2, D-79104 Freiburg, Germany Univ Regensburg, Lehrstuhl Mikrobiol, D-8400 Regensburg, Germany Univ Regensburg Regensburg Germany D-8400 ol, D-8400 Regensburg, Germany
Titolo Testata:
JOURNAL OF BACTERIOLOGY
fascicolo: 4, volume: 181, anno: 1999,
pagine: 1088 - 1098
SICI:
0021-9193(199902)181:4<1088:POACA(>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
SP-NOV REPRESENTS; ARCHAEBACTERIUM THERMOPROTEUS-NEUTROPHILUS; EUBACTERIUM CHLOROFLEXUS-AURANTIACUS; MONOXIDE DEHYDROGENASE PATHWAY; TRICARBOXYLIC-ACID CYCLE; CHLOROBIUM-LIMICOLA; AQUIFEX-PYROPHILUS; GEN-NOV; ENZYMES; ASSIMILATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
47
Recensione:
Indirizzi per estratti:
Indirizzo: Fuchs, G Univ Freiburg, Inst Biol 2, Schanzlestr 1, D-79104 Freiburg, Germany Univ Freiburg Schanzlestr 1 Freiburg Germany D-79104 rg, Germany
Citazione:
C. Menendez et al., "Presence of acetyl coenzyme A (CoA) carboxylase and propionyl-CoA carboxylase in autotrophic Crenarchaeota and indication for operation of a 3-hydroxypropionate cycle in autotrophic carbon fixation", J BACT, 181(4), 1999, pp. 1088-1098

Abstract

The pathway of autotrophic CO2 fixation was studied in the phototrophic bacterium Chloroflexus aurantiacus and in the aerobic thermoacidophilic archaeon Metallosphaera sedula. In both organisms, none of the key enzymes of the reductive pentose phosphate cycle, the reductive citric acid cycle, and the reductive acetyl coenzyme A (acetyl-CoA) pathway were detectable. However, cells contained the biotin-dependent acetyl-CoA carboxylase and propionyl-CoA carboxylase as well as phosphoenolpyruvate carboxylase, The specific enzyme activities of the carboxylases were high enough to explain the autotrophic growth rate via the 3-hydroxypropionate cycle. Extracts catalyzed the CO2-, MgATP-, and NADPH-dependent conversion of acetyl-CoA to 3-hydroxypropionate via malonyl-CoA and the conversion of this intermediate to succinate via propionyl-CoA. The labelled intermediates were detected in vitro with either (CO2)-C-14 or [C-14]acetyl-CoA as precursor. These reactions are part of the 3-hydroxypropionate cycle, the autotrophic pathway proposed For C. aurantiacus. The investigation was extended to the autotrophic archaea Sulfolobus metallicus and Acidianus infernus, which showed acetyl-CoA and propionyl-CoA carboxylase activities in extracts of autotrophically grown cells. Acetyl-CoA carboxylase activity is unexpected in archaea since they do not contain fatty acids in their membranes. These aerobic archaea, as well as C. aurantiacus, were screened for biotin-containing proteins by the avidin-peroxidase test. They contained large amounts of a small biotin-carryingprotein, which is most likely part of the acetyl-CoA and propionyl-CoA carboxylases, Other archaea reported to use one of the other known autotrophicpathways lacked such small biotin-containing proteins, These findings suggest that the aerobic autotrophic archaea M. sedula, S. metallicus, and A. infernus use a yet-to-be-defined 3-hydroxypropionate cycle for their autotrophic growth, Acetyl-CoA carboxylase and propionyl-CoA carboxylase are proposed to be the main CO2 fixation enzymes, and phosphoenolpyruvate carboxylase may have an anaplerotic function. The results also provide further support for the occurrence of the 3-hydroxypropionate cycle in C. aurantiacus.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 24/11/20 alle ore 14:10:17